Oil float operated switch



April 18, 1944.

w. w. WILLIAMS OIL FLOAT OPERATED SWITCH Filed June 2'7, 1941 .ZNVENTOR.WALTER MW/LL/AMS BY A TORNE YJ'.

Patented Apr. 18, 1944 UNITED STATES PATENT OFFICE OIL FLOAT oremrnoswrron Walter W. Williams, Bloomington, Ill.

Application June 2-1, 1941, Serial No. 400,071

9 Claims.

This invention relates to refrigerating units, with particular referenceto units including a compressor and oil separator, rectifier or sump-During the building up of the pressure in the crankcase, the refrigerantvapors returning from the evaporator dissolve to a material extent inthe lubricant in the crankcase, and this lubricant and dissolvedrefrigerant therein drain into a sump or chamber below th crankcase. Thepressure outlet conduit from the compressor extends through the oil inthe sump, and the high temperature of this conduit will heat thelubricant sufficiently to expel the major portion of the dissolvedvapors which have been carried into the sump with the lubricant.

In operating the compressor, it is of course necessary to retain at alltimes a sufiicient quantity of lubricant in the sump to properlylubricate the mechanism. Furthermore, it is desirable that the level ofthe lubricant in the sump should never be below the refrigerant conduitpassing therethrough, as otherwise the lubricant may not be sufllcientlyheated to vaporize the refrigerant dissolved therein.

It is, therefore, an object of the present invention to provide anautomatic means which will make the motor and associated temperaturecontrol ineffective to operate the compressor except when the lubricantlevel is at a-predetermined height relative to the refrigerant conduitin the sump.

A further object is to provide a lubricant and refrigerant control whichwill be effective to P vent operation of the unit except when thelubricant and lubricant heating means are in a predeterminedrelationship adapted to produce efiective vaporizing of dissolvedrefrigerant and efiicient lubrication of the mechanism.

Further objects will be apparent from the specification and the appendedclaims.

the drawing:

Fig. 1. 1s a side elevation partially in section of the compnessorforming a part of the usual refrigerating system.

Fig. 2 is a diagrammatic view illustrating the pressure control switch,the motor, and the lubri-' cant level control element in cooperativerelation to simultaneously control the refrigerating unit and thelubricant level associated therewith.

Fig.3 is a top view of the electrical control switch illustrated in Fig.1.

The embodiment illustrated comprises a well known type of multiplepiston compressor having cylinders i, a crankcase 2. and the usualconnecting rods 3 in driven relation with a crankshaft 4 having a pulley5 secured thereto whereby the compressor may be driven by theusualelectric motor as illustrated in Fig. 2. A sump 8 is positionedbelow the crank-case 2 and may comprise an elongated chambersubstantially as illustrated.

A drainpipe 1 leads from th crankcase into the sump 6, whereby lubricantfrom the crankcase 2 may drain into the sump. A conduit Heads from thebottom of the sump 6 to an oil pump 9, the latter being mounted on thecasing 2 and operatively connected to the crankshaft. The oil pump 9withdraws lubricant from the bottom of the sump 6 and forces it throughsuitable conduits to the various bearing surfaces of the compressor. Aconstant circulation of lubricant to the bearings is thereby providedwhen thecompressor is in operation. The lubricant, after passing throughthe bearings, drains downwardly from the crankcase 2 through thedrainpipe I and into the sump 6, and the refrigerant vapors expelledfrom the surface of the lubricant in the sump 6 may pass upward throughthe drainpipe i into the crankcase 2 and be drawn by the pistons intothe compression cylinders, while at the same time the substantially purelubricant at the bottom of the sump 5 is circulated through the workingparts of the compressor by means of the pump 9. Also,

if desired, a conduit in may be provided leading from the top of thesump 6 to the top of the crankcase 2, through which the refrigerantvapors expelled from the lubricant may be conducted to 1 the upper partof the crankcase 2 closely adjacent the cylinders.

In order to heat the lubricant in the sump 6, the compressor outletconduit ll leads from the top of the cylinders l to the sump 5 and aportion Ha of this conduit ii extend preferably horizontally through thesump 6 in a position to be submerged in, or at least sufficiently incontact with, the lubricant to cause vaporization of the dissolvedrefrigerant. In operation, the level 2| of the body of lubricant inthesump is preferably materially above the conduit I la. Therefore, the

lubricant will be heated sufficiently to expel the electrical controlcir it. including the usual 1 dissolved refrigerant vapors from thelubricant.

In order to maintain at all times a suiilcient amount of lubricant inthe siunp i to contact the necessary area of the heating conduit Ha sothat the lubricant will maintain the required temperature, a floatoperated switch is provided for making ineflective' the operation of theusual motor and the usual pressure controlled switch associatedtherewith, when the lubricant in the sump 6 reaches a predeterminedminimum low level. The float operated switch comprises a float l2mounted on the end of a short arm 13, the arm being pivoted at ll on abracket l5 secured to the end wall of the sump. A mercury switch ii ofwell known type is supported on the float l2 and arm l3, as shown inFig. 3, a nd is tiltable in response to movement of the float inaccordance with variations in the lubricant level. The positioning ofthe switch [6 may be adjusted by an adjusting screw Ila. The switch I6is connected in series with and between a motor l1 and a pressurecontrol switch l8 in a power circuit l9, as illustrated in Fig. 2, thepower circuit being initially controllable by means of a main switch 20.When the lubricant level 2| is above the level indicated by the dottedline Zia in Fig. l, the mercury switch [6 will be retained in onposition so that the unit may operate in the usual manner under thecontrol of th low pressure switch l8, and when the lubricant reaches apredetermined low level, such for instance as indicated by the dottedline Zia, the float switch will then be positioned to break the motorcircuit and the motor will not operate in response to action of the lowpressure control switch It until more lubricant has been introduced intothe sump 5.

To prevent adversely affecting the mercury switch i5 by variations intemperature and pressure, the float I2 is provided on its upper sidewith a small vent conduit l2a.

It is intended, of course, that the invention should not be limited tothe specific embodiment or embodiments disclosed herein, sincemodifications may be made, and it is contemplated, therefore, by theappended claims to cover any such modifications as fall within the truespirit and scope of this invention.

Having thus described this invention, what is claimed and desired to besecured by Letters Patent is:

1. In a sealed refrigerating system including a compressor having acrankcase and lubricant reservoir therefor forming apart of said sealedsystem, means for circulating'lubricant from said reservoir through theoperating mechanism of said compressor and returning the said lubricantto said reservoir, a motor for operating said compressor, means operableby refrigerant pressure in said system to cause intermittent operationof said motor, and additional means controlled by the lubricant level insaid reservoir to make said motor ineffective to operate said compressorwhen the lubricant level in said reservoir is at or below apredetermined level.

2. In a sealed refrigerating system including a compressor having acrankcase forming a part of said sealed system, an oil supply for saidcompressor, a motor for operating said compressor,

'said compressor and returning the said lubricant to said reservoir, amotor for operating said compressor, a low pressure control meansassociated with said motor and said sealed system for controlling saidmotor in accordance with variations in pressure in said sealed system,and float operated means in said reservoir for making said motorineffective for normal operation when the lubricant in said reservoir-is below the predetermined level.

5. In a sealed refrigerating system including a compressor having acrankcase and lubricant reservoir therefor forming a part of said sealedsystem, means for circulating lubricant from said reservoir through theoperating mechanism of said compressor and returning the said lubricantto said reservoir, an electric motor for operating said compressor, alow pressure control means associated with said motor and said sealedsystem for controlling said motor in accordance with variations inpressure in said sealed system, float operated means in said reservoirfor making said motor ineffective for normal operation when thelubricant in said reservoir is below a predetermined level, and heatingmeans in said reservoir extending at least partially below saidpredetermined level.

6. In a sealed refrigerating system including a compressor having acrankcase and lubricant reservoir therefor forming a part of said sealedsystem, means for circulating lubricant from said reservoir through theoperating mechanism of said compressor and returning the said lubricantto said reservoir, an electric motor for operating said compressor, anelectrical circuit for said motor, a switch controlled by the pressurein said system for alternatively making and breaking said circuit, andmeans controlled by the level of said lubricant to control theeffectiveness of said circuit.

'7. The combination with a sealed refrigerating system including acompressor having the usual crankcase as a part of said sealed system, apressure lubricating system for said compressor and a separate sealedsump below said crankcase and having one or more conduit connectionstherewith for oil drainage to said sump and gas return to saidrefrigerating system, anda high pressure refrigerant conduit in saidsump in heat transfer contact with said lubricant, of a motor foroperating said compressor, a motor circuit, a normally closed switch insaid circuit, and a float in said sump arranged to open said switch whenthe lubricant falls below a predetermined level relative to saidconduit.

8. The combination with a sealed refrigerating system including acompressor, a lubricant sump, and a pump for circulating said lubricantthrough said compressor and said sump, of an electric motor foroperating said compressor, an automatic low pressure control switch forthe motor said compressor and returning the said lubricant to saidreservoir, a high pressure refrigerant conduit in said reservoir in heattransfer contact with said lubricant for vaporizingrefrigerant dissolvedWithin said lubricant prior to circulation thereof through saidoperating mechanism, and means controlled by the lubricant level in saidreservoir for causing intermittent operation of said compressor, saidconduit being positioned within said reservoir so as to be at all timesat least partially immersed in the lubricant while 10 said compressor isoperating.

WALTER W. WILLIAMS.

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